The cell membrane keeps us alive. But in doing so, it carries out a big task, a complex task, one that requires for the cell membrane to be built of many different components.
All membranes in a cell have the same basic structure. The cell surface membrane which separates the cell from its external environment is known as the plasma membrane. The membrane is very important and is formed from a phospholipid bilayer, which is the foundation. It is made up of hydrophilic phosphate heads, of which the phoshpholipids form both the inner and outer surface of a membrane. The fatty acid tails of the phosholipids form a hydrophobic core inside the membrane.
Cells are made to exist in aqueous environments, and the inside of cells and organelles are also usually aqueous environments. For this reason the phospholipid bilayers are perfectly suited as membranes because the outer surfaces of the hydrophilic phosphate heads can interact with water.